Stimulating Effect of Ethanol on Erythropoietin Production in the Liver Cells

Increased erythropoietin (EPO) production is important for erythropoiesis as well as cell viability. The most effective factor for promoting EPO production is hypoxia, which alters the redox state and produces a reducing environment in the cell. In this study, we examined the influence of ethanol on EPO production in HepG2 cells to investigate the effect of increasing the free NADH/NAD+ ratio in the cytosol during normoxia. Ethanol treatment increased the lactate/pyruvate ratio, an index of the cytosolic redox state, in a dose-dependent manner, with maximal promotion of EPO production observed at 300 μM ethanol. These results suggest that altering the cytosolic NADH/NAD+ redox state to the same degree as hypoxia is effective in promoting EPO production. Ethanol (300 μM) increased mRNA expression and protein levels of sirtuin1, which is a transcription factor, related to both hypoxia inducible factor and cytosolic redox state, whereas 2000 μM ethanol did not produce these effects. Although the sirtuin1 inhibitorEX-527 did not affect the lactate/pyruvate ratio, EX-527 inhibited the induction of EPO mRNA expression by 300 μM ethanol. In rat primary hepatocytes and kidney cells, 300 μM ethanol increased sirtuin1 and EPO mRNA expression, as well as EPO concentrations in media. In conclusion, we showed low concentrations of ethanol promote EPO production by increasing sirtuin1 in HepG2 cells, as well as primary liver and kidney cells. The use of ethanol represents a hypoxia-independent method to promote EPO production.